Retainer for an over-centre fastener

ABSTRACT

A retainer for an adjustment device for an over-center fastener for securing and clamping two parts ( 11, 12 ) together by applying a pulling force between the parts by a lever ( 14 ). The adjustment device includes an externally threaded member ( 17   a ) and an internally threaded member ( 19 ) rotatable relative to one another. The internally threaded member has a friction increasing insert ( 24 ) preventing unintentional relative rotation between the externally threaded member and the internally threaded member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a retainer for an adjustment device of anover-center fastener.

2. Description of the Related Art

Over-center fasteners (also denominated toggle fasteners or latches) arecommonly used for securing—and often clamping—two objects together, suchas keeping a lid in a closed position on a box or case. A first part ofthe fastener, referred to as a striker and often having a hook-likeshape, is attached to one of the objects. A base member of the otherpart of the fastener is attached to the other object.

There are two different types of over-center fasteners.

In a first type (see e.g.: http://www.ojop.com/700.htm), a first end ofa lever is jointed to the base member so as to be swingable about afirst axis. The other end of the lever serves as a handle member. At adistance from the first end, an engagement means is linked to the leverso as to be swingable about a second axis parallel to the first axis. Inuse, the engagement means is brought into engagement with the first partof the fastener and the handle with the second axis is swung about thefirst axis to move the engagement means closer to the base member. Inorder to vary the distance between the second axis and the engagementmeans, and thereby the engagement force, the engagement means has athreaded stem member engaged in the threads of an internally threadedbody member rotatably connected to the lever about the second axis. Thebody member is normally a cylindrical body rotatable about its axis.

In a second type of over-center fastener (see e.g.:http://www.ojop.com/900.htm), a first end of a link is jointed to thebase member so as to be rotatable about a first axis. A second end ofthe link is jointed to a first end of a handle member. A second end ofthe handle member is provided with engagement means for engagement withthe first part of the fastener. In use, the engagement means is broughtinto engagement with the first part of the fastener, and the handlemember is operated, involving rotation of the second axis about thefirst one, thereby moving the engagement means closer to the first part.In order to vary the distance between the first and the second axes, thelength of the link is variable in that it comprises a threaded stemmember engaged in an internally threaded body member connected to thehandle and containing the second axis. In this case, the body member isusually formed from folded sheet metal.

In both types of fasteners, there is a desire to prevent undesiredrelative rotation of the two threaded members. Such rotation oftenoccurs due to vibrations or other exterior influence in the unlocked andunloaded state of an over-center fastener, and may result in that aparticular setting of the fastener for a particular clamping case may belost. This, in turn, may result in that clamping becomes too loose or totight, or, in case such condition is discovered at all, in a timeconsuming renewed setting.

SUMMARY OF THE INVENTION

Thus, the problem to be solved by the present invention, and that musthave existed for at least a century, is to provide a means for retainingundesired relative rotation of the externally threaded stem and theinternally threaded body of an over-center fastener.

According to the present invention this problem is solved by applyingwhat is previously known from various lock nuts, viz., the use of africtional insert, to an over-center fastener.

In practice, this may be accomplished by simply using a conventionallock nut as the internally threaded body, or, by providing theinternally threaded body with a friction increasing insert.

In the lock nut case, in the first type of fastener, it is sufficient tocut a rectangular aperture through the body member extending at rightangle to its rotational axis and at the same time at right angle to itsthrough hole, which is no longer threaded but a smooth hole having aninternal diameter slightly larger than the external diameter of thethread of the threaded stem member. The dimensions of the aperture aresuch that a nut is un-rotationally accommodated within it.

In the lock nut case, in the second type of fastener, there is provideda holder for a nut connected to the handle member to be rotatable aboutthe second axis. The holder is formed from sheet metal to receive thenut in an unrotational manner.

In the friction increasing insert case, it is proposed still to use theprior art internally threaded body member, but to complete it with afriction increasing insert similarly to what is known from conventionallock nuts.

BRIEF DESCRIPTION OF THE DRAWING

Embodiments of the present invention will now be described, referencebeing made to the accompanying drawings, wherein:

FIG. 1 is a side view of a state of art fastener of the first type;

FIG. 2 is a plan view of the fastener of FIG. 1 shown without itsassociated striker;

FIG. 3 is a plan view corresponding to FIG. 2 of a fastener providedwith a lock nut according to the present invention;

FIG. 4 is a part cross sectional side view of a fastener of the secondtype provided with a lock nut according to the present invention andshown in a partially open position;

FIG. 5 is a cross sectional side view of the fastener of FIG. 4 in alocked position;

FIG. 6 is a plan sectional view taken along line VI—VI in FIG. 5;

FIG. 7 is a plan view of a fastener similar to that according to FIGS. 1and 2 provided with a cylindrical, internally threaded body having afriction increasing insert according to the present invention;

FIG. 8 is a view corresponding to FIG. 7 but showing the cylindricalbody and portions of the lever sectioned;

FIG. 9 is a section through the cylindrical body of FIG. 8 at anenlarged scale;

FIG. 10 is a view towards the side of the cylindrical body according toFIGS. 7–9 carrying the insert;

FIG. 11 is a section taken along line XI—XI in FIG. 10;

FIG. 12 is a view corresponding to that of FIG. 10 of an embodiment ofinternally threaded body having a square cross section;

FIG. 13 is a section taken along line XIII—XIII in FIG. 12;

FIG. 14 is a section taken along line XIV—XIV in FIG. 12;

FIG. 15 is a view corresponding to that of FIGS. 10 and 12 of anembodiment of internally threaded body having a hexagonal cross section;

FIG. 16 is a section taken along line XVI—XVI in FIG. 15; and

FIG. 17 is a section taken along line XVII—XVII in FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

The state of art fastener shown in FIGS. 1 and 2 is shown to connect andclamp together two separate pieces 11 and 12. It includes a first part13—a striker—fixed to the first piece 11, and a second part 14 fixed tothe second piece 12. The striker has a hook-like free end 13 a. Thesecond part comprises a base plate 15 fixed to the second piece 12, alever 16 and an engagement member 17. The lever 16 is swingable aboutrivets 18 a, 18 b engaged in spaced brackets 15 a, 15 b protruding fromthe base plate 15. A first end 17 a of the engagement member 17 isthreaded and engages internal threads of a cylindrical body 19 which islinked to the lever 16 at a distance from the rivets 18 a, 18 b. Moreprecisely, the cylindrical body 19 is carried between spaced legs 16 a,16 b of the lever 16 so as to be rotational about stub shafts 21 engagedin the spaced legs. A free end of the engagement member 17 is formedwith an eye 17 b engaging the hook-like end 13 a of the striker 13 inthe locked position shown in FIG. 1. In the unclamped state of theengagement member, its threaded end is likely to disengage from thethreads of the body 19 due to, for instance, vibrations. To overcomethis risk, the present invention proposes to use a conventional locknut, for instance of the kind having a friction increasing inlay at oneend of its internal threads.

FIG. 3 shows how this may be realized in a fastener of the kind shown inFIGS. 1 and 2. A rectangular aperture 22 is machined through thecylindrical body 19′ and a lock nut 23, having a width between two ofits opposed sides 23 a, 23 b slightly greater than the free width of theaperture 22, is introduced into the aperture. Thereafter, the threadedend 17 a of the engagement member is threaded through the nut and afriction increasing inlay 24 provided at one of its ends. The internalthreads of the cylindrical block may be maintained, although it ispreferred not to have such threads in this case, since they mayinterfere with the threads of the nut when mounting the threaded end ofthe engagement member.

The inventive idea applied to the second type of fastener is shown inFIGS. 4–6, wherein the same reference numerals are used as in FIGS. 1–3for corresponding parts.

As in the previous embodiment, a first piece 11 is to be clamped to asecond piece 12 (FIGS. 4 and 5) by means of a fastener. The fastener isshown in FIG. 4 to be in a partly open state and in FIG. 5 to be closed,having clamped the two pieces together. A striker 13′ is attached to thefirst piece 11 and a base plate 15 is attached to the second piece 12.Again, the base plate has spaced brackets 15 a, 15 b. A cylindrical body25 is rotatably carried between the brackets by means of stub shafts 26a, 26 b engaged in a respective bracket. A stem 27 having threads 27 aat one end has a reduced diameter opposed end 27 b extending through adiametrically extending hole 28 through the cylindrical body 25. Thestem end 27 b is jolted at 29 so as to firmly keep the stem in relationto the hole 28 and the cylindrical body.

A handle member 30 of inverted U-shaped cross section has spaced flangeportions 30 a, 30 b and a hooked forward end 30 c for engagement withthe striker 13′.

A bent sheet metal structure 31 has a generally inverted U-shapedportion including opposed flange portions 31 a, 31 b and a web portion31 c. The flange portions are linked to a respective flange portion 30a, 30 b of the handle member 30 by means of rivets 32 a, 32 b,respectively. The web portion 31 c carries an integral extension 33. Afirst portion 33 a of the extension is bent at substantially 90° so asto extend along and abut a respective forwardly directed edge 34 of theflange portions 30 a, 30 b. A second portion 33 b of the extension isbent at 90° in relation to the first portion, and a third portion 33 cthereof is further bent at 90° in relation to the second one. Flapportions 33 f originally extending in opposite directions from the thirdportion are bent towards the first portion 33 a so as to be mutuallyparallel, thus forming a nut retaining pocket 35. The distance betweenthe flap portions 33 f is slightly greater than the width betweenopposed surfaces 23 a, 23 b of a lock nut 23 received within the pocket35 so as to unrotationally keep the nut therein. Holes 36, 37 for thethreaded portion 27 a of the stem 27 are provided in the third and firstportions 33 c, 33 a of the extension 33.

It will be realized that in operation of the fastener, the extension 33,and particularly its third portion 33 c with its flap portions 33 f,will be exposed to only minor stresses keeping the nut unrotational,whereas the clamping forces will be transferred from the stem 27 throughthe nut and into the first portion 33 a of the extension, which abutsthe edges 34, thus directing the clamping forces into the opposedflanges of the structure 31.

In the embodiment of the present invention shown in FIGS. 7 and 8, theconventional, internally threaded body 19 is completed with a frictionincreasing insert resembling that of a conventional lock nut.

The enlarged section of FIG. 9 more clearly shows a diametricallyextending hole 35 through the body 19 provided with its internal threads35′. The hole has a widened diameter end portion 35″ at one end, and afriction increasing insert 36 is received within that end portion so asto rest against a step 37. The edge of the widened end portion is upsetat diametrically opposed locations A, B (FIG. 10) so as to positivelykeep the insert 36 in place. Like in a conventional lock nut, theinternal diameter of the insert is smaller than the external diameter ofthe threaded end 17 a of the engagement member 17. A preferred materialof the insert is Nylon®.

As one alternative to the cylindrical shape of the internally threadedbody 19 it may be advantageous to provide an internally threaded body 38having a substantially square cross section as shown in FIGS. 12–14, orto provide an internally threaded body 39 having a hexagonal crosssections as shown in FIGS. 15–17. Such cross sections provide theopportunity to make both ends of the hole 35 in flat opposed surfaces ofthe respective body. Also, a flat surface enables upsetting the edge ofthe widened portion of the hole 35 at more than the two diametricallyopposed locations A and B shown in FIG. 12, viz. also at diametricallyopposed locations C and D.

1. A retainer for an adjustment device for an over-center fastener forsecuring and clamping two parts together by applying a pulling forcebetween said two parts by a lever, said adjustment device comprising: anexternally threaded member and an internally threaded member rotatablerelative to one another, said internally threaded member being a locknut having a friction increasing insert and being unrotationally held bya structure movable with the lever, wherein said structure is a bentsheet metal structure having a generally inverted U-shaped portionincluding opposed flange portions and a web portion the flange portionsbeing linked to a respective flange portion of the lever and the webportion carrying an integral extension, a first portion of saidextension being bent at substantially 90° so as to extend along and abuta respective forwardly directed edge of the flange portions, a secondportion of said extension being bent at 90° in relation to the firstportion, and a third portion of said extension being further bent at 90°in relation to the second portion; flap portions originally extending inopposite directions from the third portion being bent towards the firstportion so as to be mutually parallel, thus forming a nut retainingpocket.
 2. The retainer according to claim 1, wherein a distance betweenthe flap portions is slightly greater than a width between opposedsurfaces of the lock nut received within the pocket so as tounrotationally keep the nut therein.
 3. The retainer according to claim1, further comprising: holes for the threaded member provided in thethird and first portions the extension.
 4. The retainer according toclaim 2, further comprising: holes for the threaded member provided inthe third and first portions of the extension.